The courts and corridors or passages shall not be used for storage purposes, nor for any purpose whatsoever except for exit and entrance, and must be kept free and clear during performances.
All courts and corridors at points of street entrance or exit must be flush with sidewalk. To overcome any difference of level in and between courts, corridors, lobbies, passages and aisles on the ground floor, gradients shall be employed of not over 1 foot in 10 feet, except that runs of not more than 10 feet in length may be 1 in 8.
A fire wall built of brick or concrete not less than 12 inches thick at any portion shall separate the auditorium from the stage and shall extend at least 4 feet above the stage roof, or the auditorium roof if the latter be higher. Any windows in the structure above the auditorium which face over roof of stage section when within 100 feet of the stage roof must be protected with fire shutters or wired glass windows in metal sashes and frames. Above the proscenium opening there shall be a girder or other support of sufficient strength to safely carry the load. If a girder be used it shall be protected against fire by at least 4 inches of fireproof material with special provision to reinforce or support it.
The proscenium opening shall be provided with a rigid fireproof curtain, built in conformity with the following specifications, or their equivalent in efficiency when approved by the Building Inspector.
The curtain shall have a rigid, rivet-jointed, steel framework. The front or audience side of the frame shall be covered with sheet steel of a thickness not less than No. 16 U. S. gauge. The back shall be covered with vitrified cellular asbestos boards at least 1 inch thick, or other material equally fire resisting. Both coverings shall be securely attached to the framework and the joints properly sealed. The curtain shall be designed to resist a wind pressure of 10 pounds per square foot of surface without flexure sufficient to interfere with its closing.
The thickness of the curtain shall be not less than 3 inches where the width of the proscenium wall opening is 30 feet or less, and curtains for larger openings shall increase in thickness in proportion to the increase in width of opening they cover.
An asbestos roll of a diameter not less than one-half the thickness of the curtain, shall be securely attached to the bottom of the curtain to form a smoke seal between the curtain and the stage.
The curtain shall overlap the proscenium wall opening at least 12 inches at each side of the opening and not less than 2 feet at the top.
The guide members at the sides shall be rolled steel shapes, none of which shall be less than 3/8 inch thick, and shall be of such character as to form a continuous smoke stop from top to bottom, with a clearance of not over 3/8 inch, except that 1 inch shall be allowed at each edge of curtain to provide for lateral expansion. They shall be installed in such manner that in case of fire on the stage the pressure of heated gases against the curtain will act to close the guide joints tightly. Provision shall be made to prevent the curtain from getting out of the guiding channel into which it shall project at least 2 inches. The proscenium wall shall have an offset at each side of the opening, so located and of such thickness and height as to be suitable for the attachment of the curtain guides.
The wall over the proscenium opening shall be smooth and plumb to approximately the top of the curtain when it is down, and shall then offset at least 4 inches for the rest of its height, thus leaving a bench along the line of the top of the curtain between which a smoke seal shall be formed. Such a seal may conveniently be provided by arranging for the edge of a rolled steel shape attached to the curtain to dip into a trough of sand resting on the bench.
No part of a curtain or any of the curtain guides shall be supported by, or fastened to, any combustible material.
The hoisting apparatus for the curtain shall be designed with a factor of safety of 8.
The points for curtain suspension shall always be an even number, but never less than four. Two of the suspension points shall be located at the extreme ends of the curtain, and the others may be placed at such points as best suit the design, but in no case shall the distance between any two points of support exceed 10 feet.
Half of the cables attached to these points shall lead to one set of counterweights and half to another. The curtain shall be operated by hydraulic or other mechanism approved by the Building Inspector. If hydraulic mechanism is used, the water may be taken from either the house tank or sprinkler tank supply. If from the latter, the supply pipe for curtain mechanism shall be so located in the tank that it cannot reduce the quantity of water below the amount necessary to fulfill the sprinkler requirements.
The device for controlling the curtain shall be simple in design, and capable of convenient operation from both sides of the stage and from the tie galleries.
The drop speed of the curtain shall be uniform and not less than 1 foot per second, but when the curtain is about 2 1/2 feet from the stage it shall automatically slow down so as to settle on the stage without shock. In addition to the regular operating mechanism, there shall be an emergency device which will cut off the power and allow the curtain to drop by gravity. This device shall be so arranged that it can be easily operated by hand from each side of the stage, under the stage, and in the tie galleries. The device shall also be so designed that its operation will be controlled by fusible links located at each of the above named points.
The audience side of the curtain may be decorated with a paint in which no oil is used. No combustible material shall be applied or attached to the curtain.
Drawings for every such curtain shall be submitted to the Building Inspector, and be approved by him before it is erected.